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<meta name="description" content="业务背景很多时候，业务有定时任务或者定时超时的需求，当任务量很大时，可能需要维护大量的timer。比如APP实时消息通道系统，对每个用户会维护一个APP到服务器的TCP连接，用来实时收发消息，对这个TCP连接，有这样一个需求：“如果连续30s没有请求包（例如登录，消息，keepalive包），服务端就要将这个用户的状态置为离线”。其中，单机TCP同时在线量约在10w级别，keepalive请求包大">
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<meta property="og:description" content="业务背景很多时候，业务有定时任务或者定时超时的需求，当任务量很大时，可能需要维护大量的timer。比如APP实时消息通道系统，对每个用户会维护一个APP到服务器的TCP连接，用来实时收发消息，对这个TCP连接，有这样一个需求：“如果连续30s没有请求包（例如登录，消息，keepalive包），服务端就要将这个用户的状态置为离线”。其中，单机TCP同时在线量约在10w级别，keepalive请求包大">
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<meta name="twitter:description" content="业务背景很多时候，业务有定时任务或者定时超时的需求，当任务量很大时，可能需要维护大量的timer。比如APP实时消息通道系统，对每个用户会维护一个APP到服务器的TCP连接，用来实时收发消息，对这个TCP连接，有这样一个需求：“如果连续30s没有请求包（例如登录，消息，keepalive包），服务端就要将这个用户的状态置为离线”。其中，单机TCP同时在线量约在10w级别，keepalive请求包大">



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          <h1 class="post-title" itemprop="name headline">10w定时任务，如何高效触发</h1>
        

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        <h3 id="业务背景"><a href="#业务背景" class="headerlink" title="业务背景"></a>业务背景</h3><p>很多时候，业务有定时任务或者定时超时的需求，当任务量很大时，可能需要维护大量的timer。<br>比如APP实时消息通道系统，对每个用户会维护一个APP到服务器的TCP连接，用来实时收发消息，对这个TCP连接，有这样一个需求：“如果连续30s没有请求包（例如登录，消息，keepalive包），服务端就要将这个用户的状态置为离线”。<br>其中，单机TCP同时在线量约在10w级别，keepalive请求包大概30s一次，吞吐量约在3000qps。</p>
<h3 id="实现方法"><a href="#实现方法" class="headerlink" title="实现方法"></a>实现方法</h3><h4 id="轮询扫描法"><a href="#轮询扫描法" class="headerlink" title="轮询扫描法"></a>轮询扫描法</h4><ul>
<li>用一个<code>Map&lt;uid, last_packet_time&gt;</code>来记录每一个uid最近一次请求时间last_packet_time</li>
<li>当某个用户uid有请求包来到，实时更新这个Map</li>
<li>启动一个timer，当Map中不为空时，轮询扫描这个Map，看每个uid的last_packet_time是否超过30s，如果超过则进行超时处理</li>
</ul>
<p>这个方案只需要启动一个timer，但是需要轮询所有记录，效率较低</p>
<h4 id="多timer触发法"><a href="#多timer触发法" class="headerlink" title="多timer触发法"></a>多timer触发法</h4><ul>
<li>用一个<code>Map&lt;uid, last_packet_time&gt;</code>来记录每一个uid最近一次请求时间last_packet_time</li>
<li>当某个用户uid有请求包来到，实时更新这个Map，并同时对这个uid请求包启动一个timer，30s之后触发</li>
<li>每个uid请求包对应的timer触发后，看Map中，查看这个uid的last_packet_time是否超过30s，如果超过则进行超时处理</li>
</ul>
<p>这个方案不需要轮询，但每个请求包要启动一个timer，比较耗资源，特别在同时在线量很大时，CPU负载就会很高。</p>
<h4 id="环形队列法"><a href="#环形队列法" class="headerlink" title="环形队列法"></a>环形队列法</h4><ul>
<li>创建一个index从0到30的环形队列（本质是个数组）</li>
<li>环上每一个slot是一个<code>Set&lt;uid&gt;</code>，任务集合</li>
<li>同时还有一个<code>Map&lt;uid, index&gt;</code>，记录每个uid落在环上的哪个slot里</li>
<li>启动一个timer，每隔1s，在上述环形队列中移动一格，0-&gt;1-&gt;2-&gt;3-&gt;…-&gt;29-&gt;30-&gt;0-&gt;…</li>
<li>有一个 currentIndex 指针来标识刚检测过的slot</li>
</ul>
<p>当有某用户uid有请求到达时：</p>
<ul>
<li>从<code>Map&lt;uid, index&gt;</code>中查找出这个uid存储在哪一个slot里</li>
<li>从对应slot的<code>Set&lt;uid&gt;</code>中，删除这个uid</li>
<li>将uid重新加入到 currentIndex 指针所指向的上一个slot中，因为这个slot，会被timer在30s之后扫描到</li>
<li>更新<code>Map&lt;uid, index&gt;</code>，保存这个uid对应slot的index值</li>
</ul>
<p>currentIndex 每秒种移动一个slot，这个slot对应的<code>Set&lt;uid&gt;</code>中所有uid都会被集体超时。当没有超时用户时，currentIndex 扫到的每一个slot的<code>Set&lt;uid&gt;</code>中应该都没有元素。</p>
<p>这个方案只需要1个timer，并且timer每1s只需要一次触发，消耗CPU很低，能够做到批量超时，currentIndex 扫到的slot，<code>Set&lt;uid&gt;</code>中所有元素都会被超时。</p>
<p>java实现：<br><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br><span class="line">94</span><br><span class="line">95</span><br><span class="line">96</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">Test</span> </span>&#123;</span><br><span class="line">    <span class="comment">/**</span></span><br><span class="line"><span class="comment">     * 环形队列</span></span><br><span class="line"><span class="comment">     */</span></span><br><span class="line">    <span class="keyword">private</span> <span class="keyword">static</span> List&lt;Set&lt;Integer&gt;&gt; queue = <span class="keyword">new</span> ArrayList&lt;Set&lt;Integer&gt;&gt;();</span><br><span class="line">    <span class="comment">/**</span></span><br><span class="line"><span class="comment">     * 指针记录</span></span><br><span class="line"><span class="comment">     */</span></span><br><span class="line">    <span class="keyword">private</span> <span class="keyword">static</span> Map&lt;Integer, Integer&gt; record = <span class="keyword">new</span> HashMap&lt;Integer, Integer&gt;();</span><br><span class="line">    <span class="comment">/**</span></span><br><span class="line"><span class="comment">     * 当前指针</span></span><br><span class="line"><span class="comment">     */</span></span><br><span class="line">    <span class="keyword">private</span> <span class="keyword">static</span> <span class="keyword">volatile</span> Integer currentIndex = <span class="number">0</span>;</span><br><span class="line">    <span class="comment">/**</span></span><br><span class="line"><span class="comment">     * 超时时长(单位：秒)</span></span><br><span class="line"><span class="comment">     */</span></span><br><span class="line">    <span class="keyword">private</span> <span class="keyword">static</span> Integer timeOut = <span class="number">30</span>;</span><br><span class="line"></span><br><span class="line">    <span class="keyword">private</span> <span class="keyword">static</span> SimpleDateFormat format = <span class="keyword">new</span> SimpleDateFormat(<span class="string">"hh:mm:ss"</span>);</span><br><span class="line"></span><br><span class="line">    <span class="function"><span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title">main</span><span class="params">(String[] args)</span> <span class="keyword">throws</span> InterruptedException </span>&#123;</span><br><span class="line">        <span class="comment">//初始化环形队列</span></span><br><span class="line">        <span class="keyword">while</span> (queue.size() &lt;= timeOut) &#123;</span><br><span class="line">            queue.add(<span class="keyword">new</span> HashSet&lt;Integer&gt;());</span><br><span class="line">        &#125;</span><br><span class="line">        <span class="comment">//timer线程</span></span><br><span class="line">        <span class="keyword">new</span> Thread(<span class="keyword">new</span> Runnable() &#123;</span><br><span class="line">            <span class="meta">@Override</span></span><br><span class="line">            <span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">run</span><span class="params">()</span> </span>&#123;</span><br><span class="line">                <span class="keyword">while</span> (<span class="keyword">true</span>) &#123;</span><br><span class="line">                    Set&lt;Integer&gt; timeOutUid = queue.get(currentIndex);</span><br><span class="line">                    System.out.println(<span class="string">"当前时间："</span> + format.format(<span class="keyword">new</span> Date()) + <span class="string">",超时用户:"</span> + timeOutUid);</span><br><span class="line">                    timeOutUid.clear();</span><br><span class="line">                    moveIndex();</span><br><span class="line">                    sleep(<span class="number">1000</span>);</span><br><span class="line">                &#125;</span><br><span class="line">            &#125;</span><br><span class="line">        &#125;).start();</span><br><span class="line"></span><br><span class="line">        Random random = <span class="keyword">new</span> Random();</span><br><span class="line">        <span class="comment">//模拟大量的用户请求</span></span><br><span class="line">        <span class="keyword">while</span> (<span class="keyword">true</span>) &#123;</span><br><span class="line">            Integer uid = random.nextInt(<span class="number">200</span>);</span><br><span class="line">            request(uid);</span><br><span class="line">            sleep(<span class="number">100</span>);</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line"></span><br><span class="line">    <span class="comment">/**</span></span><br><span class="line"><span class="comment">     * 接收用户请求</span></span><br><span class="line"><span class="comment">     *</span></span><br><span class="line"><span class="comment">     * <span class="doctag">@param</span> uid 用户id</span></span><br><span class="line"><span class="comment">     */</span></span><br><span class="line">    <span class="function"><span class="keyword">private</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title">request</span><span class="params">(Integer uid)</span> </span>&#123;</span><br><span class="line">        System.out.println(<span class="string">"当前时间："</span> + format.format(<span class="keyword">new</span> Date()) + <span class="string">",收到用户请求,uid:"</span> + uid);</span><br><span class="line">        <span class="comment">//获取删一个指针</span></span><br><span class="line">        Integer lastIndex = getLastIndex();</span><br><span class="line">        <span class="comment">//获取当前用户的记录指针</span></span><br><span class="line">        Integer recordIndex = record.get(uid);</span><br><span class="line">        <span class="comment">//删除旧的记录</span></span><br><span class="line">        <span class="keyword">if</span> (recordIndex != <span class="keyword">null</span>) &#123;</span><br><span class="line">            Set&lt;Integer&gt; oldQueue = queue.get(recordIndex);</span><br><span class="line">            oldQueue.remove(uid);</span><br><span class="line">        &#125;</span><br><span class="line">        <span class="comment">//存入新记录</span></span><br><span class="line">        Set&lt;Integer&gt; newQueue = queue.get(lastIndex);</span><br><span class="line">        newQueue.add(uid);</span><br><span class="line">        <span class="comment">//更新指针</span></span><br><span class="line">        record.put(uid, lastIndex);</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    <span class="comment">/**</span></span><br><span class="line"><span class="comment">     * 获取前一个指针</span></span><br><span class="line"><span class="comment">     *</span></span><br><span class="line"><span class="comment">     * <span class="doctag">@return</span></span></span><br><span class="line"><span class="comment">     */</span></span><br><span class="line">    <span class="function"><span class="keyword">public</span> <span class="keyword">static</span> Integer <span class="title">getLastIndex</span><span class="params">()</span> </span>&#123;</span><br><span class="line">        <span class="keyword">return</span> currentIndex == <span class="number">0</span> ? timeOut : currentIndex - <span class="number">1</span>;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    <span class="comment">/**</span></span><br><span class="line"><span class="comment">     * 移动指针</span></span><br><span class="line"><span class="comment">     */</span></span><br><span class="line">    <span class="function"><span class="keyword">private</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title">moveIndex</span><span class="params">()</span> </span>&#123;</span><br><span class="line">        currentIndex = currentIndex == timeOut ? <span class="number">0</span> : currentIndex + <span class="number">1</span>;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    <span class="function"><span class="keyword">private</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title">sleep</span><span class="params">(<span class="keyword">long</span> millis)</span> </span>&#123;</span><br><span class="line">        <span class="keyword">try</span> &#123;</span><br><span class="line">            Thread.sleep(millis);</span><br><span class="line">        &#125; <span class="keyword">catch</span> (InterruptedException e) &#123;</span><br><span class="line">            e.printStackTrace();</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure></p>

      
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                      "...</p>" + "</a>";
                  });

                  resultItem += "</li>";
                  resultItems.push({
                    item: resultItem,
                    searchTextCount: searchTextCount,
                    hitCount: hitCount,
                    id: resultItems.length
                  });
                }
              })
            };
            if (keywords.length === 1 && keywords[0] === "") {
              resultContent.innerHTML = '<div id="no-result"><i class="fa fa-search fa-5x" /></div>'
            } else if (resultItems.length === 0) {
              resultContent.innerHTML = '<div id="no-result"><i class="fa fa-frown-o fa-5x" /></div>'
            } else {
              resultItems.sort(function (resultLeft, resultRight) {
                if (resultLeft.searchTextCount !== resultRight.searchTextCount) {
                  return resultRight.searchTextCount - resultLeft.searchTextCount;
                } else if (resultLeft.hitCount !== resultRight.hitCount) {
                  return resultRight.hitCount - resultLeft.hitCount;
                } else {
                  return resultRight.id - resultLeft.id;
                }
              });
              var searchResultList = '<ul class=\"search-result-list\">';
              resultItems.forEach(function (result) {
                searchResultList += result.item;
              })
              searchResultList += "</ul>";
              resultContent.innerHTML = searchResultList;
            }
          }

          if ('auto' === 'auto') {
            input.addEventListener('input', inputEventFunction);
          } else {
            $('.search-icon').click(inputEventFunction);
            input.addEventListener('keypress', function (event) {
              if (event.keyCode === 13) {
                inputEventFunction();
              }
            });
          }

          // remove loading animation
          $(".local-search-pop-overlay").remove();
          $('body').css('overflow', '');

          proceedsearch();
        }
      });
    }

    // handle and trigger popup window;
    $('.popup-trigger').click(function(e) {
      e.stopPropagation();
      if (isfetched === false) {
        searchFunc(path, 'local-search-input', 'local-search-result');
      } else {
        proceedsearch();
      };
    });

    $('.popup-btn-close').click(onPopupClose);
    $('.popup').click(function(e){
      e.stopPropagation();
    });
    $(document).on('keyup', function (event) {
      var shouldDismissSearchPopup = event.which === 27 &&
        $('.search-popup').is(':visible');
      if (shouldDismissSearchPopup) {
        onPopupClose();
      }
    });
  </script>





  

  

  

  
  

  

  

  

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